Dads Offer

I am 19 I have always been close to dad and not mum, but should I be concerned its my 20th birthday shortly and dad has to take me shopping and buy me a bra, French knickers and stockings and suspenders it was a surprise to say the least, well I didn't know what to say, I am sure its not appropriate for a parent to offer to buy sexy underwear to a daughter, or maybe he is just being nice to me and there is nothing in, it I am very close to dad but not that close, I want to tell mum but I dare not because of what it would cause, has any girl out there had a similar offer,
talk to me please,

Opl56jk