Rock hard penis

Im 19 now and last week went to the doctor as i needed confirmation of full physical check been done for some insurance my mom had.

The minute his hand touched my penis it went rock hard within like 0.2 seconds flat and dont know if im just thinking it was like this but i am 99% sure he was enjoying touching me because he would squeeze on my shaft and then move up more and squeeze alittle further till he got to my head then also almost played around with it. So embarrassing and thats probably the reason i left him was because embarrassed i was rock hard.

Think he was touching my dick longer than everything else together.