It could be just a reference to the fact that she likes kissing/making out with him since a common trope in Japan is that your "first kiss" tastes like lemons. She's also holding the lemon up on her mouth in the final panel that has the guy with a surprised expression so I could see it implying she wants to kiss as a sort of *hint hint nudge nudge*.
Granted the first panel with her hand on her stomach does give the implication it may be related as well so getting some mixed signals here. Either she really is that naive about her weird cravings and doesn't realize she's pregnant (cravings during pregnancy don't start immediately, she would have noticed other more obvious signs like missing her period before that started) or the hand on stomach is just unintentionally misleading.
Personally I think it's just a lemon > kissing correlation since the ramifications are less extreme and I'd rather not make large assumptions until more evidence presents itself in later chapters.