Do any PM's that they may have sent disappear?
I was just looking through mine to check some of the info I had been sent, and all of the ones from someone who doesn't seem to be around have vanished! 
Would you think it was odd if a younger person wanted to befriend you?
‘The ‘professionals’ - finally finished, phew!



. I had vaugely assumed that they just dropped off after a certain time, or when your inbox was full. 