Sore after the first couple times of penetration...is that normal?

I feel sooo akward asking this question but i just got to. Is it normal to be sore after the first few times of penatration even if it feels good at the time? I think its the 2nd or 3rd time that iv fully done it and i enjoyed it alot but today im alittle sore, which is what happened last time. I know its normal to be sore at first but im just not sure how long thats supposed to last. And iv used lube so thats not the problem cause it didnt hurt durning it. Hope someone can help!