Am I being Paranoid?

Due to fly HKT-HEL on April 9th. The rotation on that route looks simple enough - AY151 comes in from Helsinki around 0800, and AY152 returns around 2 hours later. Simple! However - it looks like AY151 stops flying after April 5th? There are AY152s in the schedule for 6, 9, 11 and 13 of April... I'm guessing flight on the 5th could be the equipment that flew out the day before, but what about the 9th, 11th and 13th? Where are these planes coming from?