It's harmless. I ordered flowers for my girlfriend's birthday and they had a question about the address. They do have an option where you can opt in to receive anniversary/birthday reminders. If you opt in they will call and remind you and ask if you want to order. Strictly a customer service call that you agreed to if you received a reminder call.
I have not ordered from gift tree, but it is near my anniversary, so it is possible they got my number from a list sold to them by someone who sells such things. I did used to keep dates on line with FTD'd reminder service, till I realized that was an invitation for them to harass you.
By the way, no matter what size of boquet you order from FTD, the florist always delivers the small one. Always! So always order the small one so you get what you paid for. they assume that you will never see them, so you won't check up on the size. If you call them out on it, they will send you a refund, but only if you report them to the BBB, if you call or email their customer service, they will ignore you. When they issue a refund, they always blame the local florist. There was an expose on TV, and there they exposed the same issue, and suggested you should just start by buying from the local florist in the first place... but I call BS on that one, because here the locals want $110 for what I can buy from FTD for $29. So the lesson there is go small with FTD, or just pay a LOT.
Received a call from this number - I did not answer. Googled the number and it came up as Gift Tree. I have never ordered anything from them. Not sure how they got my phone number.