I've never found asking for email to draw suspicion, but I'm saying that as a Canadian in my 30's.
Common reasons to ask for email could be:
- Many registrations/forms require you provide other contacts for safety reasons (I've experienced this in school, for example)
- Wanting to send a gift (Steam game, e-card etc)
- Wanting to have it in your phone for an emergency in case you couldn't call/text them
I hope this helps, and if not, that you are OK and find what you need