Am I selfishly motivated?

This year is the 18th year of lend a helping can - for wheb, the radio station I listen to. I was going to donate $5 anyways but this morning whilst in the shower they said if one was to donate between 7am-8:30am they would be registered to win 2 tickets to see NEIL DIAMOND. AND anyone who donates is registered to win a $6,000 hearts a fire Diamond necklace from Jewelry Creations in Dover. So, I donated $10 and I am proud of myself for that but I am concerned that my donation was solely so I could possibly get something out of it.