My girlfriend questioned my fidelity

So..... I was with my gf a couple of nights ago and we haven't really been engaging in sexual activities these last few weeks because of shit that kept coming up. So we finally had some time and a brief "quickie". After we were done she asked me have I been with anyone else since the last time we had sex and of course my answer was no... simply because I haven't even had the time to have sex with MYSELF let alone her and I was kinda shocked she even asked. Fast forward a couple days later I'm still upset about it because like no one has ever questioned my vagina before so I was a bit hurt. She says I'm over reacting but I feel like she doesn't trust me to know that I'm only dealing with her. Ive never cheated on her and whatever I do, wherever I go, whoever I'm with she always knows. I thought I built enough trust in our relationship. But I guess not. Should I be feeling some type of way?