It's difficult to know your own speech habits until someone else points them out. When I was a teenager, a couple people pointed out that I said "awesome" an excessive amount (as in, a couple of times per hour). I conscientiously tried to stop using it as much. Some days, even now, I catch myself using it a few times per day. Because I'm more aware of it, I tend to watch myself more.
My dad had this speech habit where he started sentences with "Hey...." quite a bit. They tended to be questions.
"Hey...want a piece of pie?"
"Hey...is it raining?"
"Hey...what are you doing?"
Often times it just trailed off and he never finished the thought. He got in the "Hey" loop. "Hey...." I turn to him and give him my attention. "Hey...." he says again.
That was annoying when he went in the neverending "Hey" loop. Then I started saying, "Hey what?" back to him.
After he got sick with multiple sclerosis (it was unclear when the disease actually began because of his poor lifestyle), forming sentences became even more difficult for him. So it was a LOT of "Hey..." "Hey...." because when you actually say it, "Hey..." doesn't take a whole lot of vocal talent. He struggled with getting every other word out.
A few months ago this little girl I live with started saying, "Hey..."
"Hey...where'd my bear go?"
"Hey guys, come here."
Even better is the "Hey....Hey....Hey...." loop.
To my knowledge, I don't say "Hey" very much. Maybe I do and don't know. I don't think S says it either. Most likely it's a kid at school who she is mimicking. Because, really, "Hey..." 100 times a day can't actually be genetic, can it?