Chun-Li's winquote to Guile
Chun-Li to Guile: "It feels like my techniques are a bit sharper than yours. Perhaps it's just one of those days?"
I believe this winquote displays more about Chun-Li's personality and some subtle hints with her and Guile's partnership together, rather than revealing any kind of lore or story info.
Interestingly enough, Chun-Li's and Guile's winquote to each other both mention Chun-Li's techniques.
In both, Chun-Li's fighting style and techniques are still going strong, even after retirement and opening up a Kung Fu school. And it absolutely should. Even if her purpose isn't to pursue justice anymore, she still got to be at the top of her game for people to take her serious as a Sifu and community leader. (How many students do you have at your Dojo, Dan?!?!?!)
Both in regards to gameplay design and with the martial art, Guile's and Chun-Li's fighting style and moves could not be more fundamentally different. Guile's tech may be simple on the surface with Sonic Booms, Blades (which is an interesting choice in Chun using the word "sharper"), and Somersaults. But Guile puts on a lot of muscle and power into those techniques.
On the flipside, Chun-Li's kung fu is a mishmash of styles, differing degrees of difficulty, power, speed, movement, etc. Which is reflective in Chun being a much more complex and technical character than Guile. And with much more styles and techniques to constantly hone, Chun-Li staying sharp after all these years, on top of taking care of Li-Fen and running her community, is nothing short of impressive in Guile's eyes.
The final part I want to mention is the 2nd part of the quote. I interpret the "it's just one of those days" part of the quote as Chun-Li poking fun at Guile. Guile is probably one of the most serious fighters of the whole cast. Where as you see Chun-Li waving at the crowd in the pre-versus Walkouts, and having her "I Did it!" win pose back. So after working together for so long, you'd think Guile would be able to crack a smile at Chun-Li once in a while. I can imagine since Chun-Li is more of the fun-loving character between the two, she's had her chances of playful/witty banter at Guile.
Part of me wants to interpret Chun-Li is also mocking Guile that his moves aren't as sharp anymore as he's also getting up there in age. Maybe Guile's moves is lacking abit because he's also getting up there in age?
I imagine that the original "Family Man" still goes back to his family to go back to. But everyone is getting older now, even Guile's daughter. I'm curious if she's grown up and in high school or college now. With Daddy's little girl growing up, I'm curious if he has to deal with a rebellious side of his daughter, or if he tries to spend as much time with her as possible before she eventually leaves for college or gets married. I'm really curious to see Guile's family life outside of Street Fighting. Maybe that family life has opened up a soft side of Guile we might get to see in SF6?
Overall, good quote from Chun to Guile. I like it. I def feel I tend to overanalyze a little bit on these, but Chun and Guile have been working together for YEARS now. And the fact they are still friends to this day does say a lot about them as characters, and gives us much reason to question about things.