Have you ever received a pass or coupon or some favor on your birthday? Students might sometimes receive a “homework pass” on their birthday, so that they don’t have to do an assignment. Employees might sometimes get to “go home early” (with pay) on their birthday. Customers will sometimes receive coupons on their birthdays from restaurants or retailers. 
Some Christians have brought that way of thinking (i.e., receiving certain favors or rewards on our birthdays) into their Christian walk. I have heard of Christians who decided to take Sunday as a “Day for Me,” to celebrate, relax and “enjoy what I like,” and so they did not attend worship that Sunday. In their minds, it was an “excused absence” for their birthday.
There is nothing unscriptural about celebrating birthdays and receiving favors and rewards. However, when our “celebration” or our “Me Time” overrides our devotion (and obligation) to the One who gave us life, we need to sit down, reflect and earnestly examine ourselves!