Has anyone elses baby done this?

my son is a little over three months old and today when i was cutting his nails he started sucking on my arm. he love to suck on everything even when he is not hungry. i just let him and continued to cut his nails. when i was done i had a hickey like mark on my arm!!! it's still there 3 hours later! has anyone elses baby done this before? it seems like it would take a pretty strong force to make a mark like that on my lower arm doesn't it? it's about the size of a dime.