Is my girlfriend overreacting or how can I prevent this embarrassing intimate moment?

Whenever we have sex and we planned it a bit in advance everything is fine as I can go and freshen up just before we have sex.
But each time we have spontaneous sex, it is a different story. I have a very long foreskin which covers the glans all of the time. I wash myself down there every day, but after some hours I easily get a bit of smegma buildup underneath my foreskin.
My girlfriend has this quirky habit, when we are undressing each other, of completely pulling back my foreskin.
So when it is a spur of the moment thing, quite often there is a bit of smegma visible when she retracts the foreskin. She finds this disgusting, she then asks to go wash it thoroughly and sometimes asks if I didn’t clean myself down there in the morning. I find it sooo embarrassing… Do you think my girlfriend is overreacting as I wash myself everyday down there or is there anything I can do to prevent this shameful ordeal whenever we have spontaneous sex? This is ruining our sex life quite a lot… So please help and give me some advise or tell me your experiences.