Firstly, it never hurts to take her to the ped & have a unrinalysis done. It is simple and easy, just peeing in a cup.
Secondly, I highly doubt she has a UTI. My daughter went through the same thing at 4. And now, on occassion still "obsesses" about things; wet panties, wet sleeves or cuffs, aches in her body, etc.
While going through this time with my daughter, I was so frustrated, furious, mad, irritated, etc. One day I literally held her in the bathroom while she sobbed and struggled about her panties being wet. I found the wet wipes did not help the situation.
What I did do, was explain to her calmly that it is ok for a few drips to go on her panties and if she was very uncomfortable SHE could change her panties (she is now 7 and still occassionally changes her panties). I had her get her own panties herself and then she also had to help me with the extra laundry. The "wet panty syndrome" seemed to last about 3-4 months and then ended.
When my children touch themselves in public, I ask if they are ok and then remind them that if they want to touch themselves they can do so in the privacy of their bedroom or in the bathroom.
We even saw a family therapist about this and he explained it to us that our 4 year old was having a sudden mental developmental leap of imagination and it makes everything a bit more unstable and worrisome to the child. It can throw the child into some "OCD" actions but not to worry unless the OCDness starts to undermine the progress of their day.
Good luck. Keep calm. And just let her change her panties while also helping you with the additional laundry load. I hope what worked for me will work for you.
Fondly,
ann m.