The Hobie 15 is a Hobie Europe product that not been imported to North America.
From the image above, it appears it has a step similar to the 17 / 20 / Tiger.
It's not a concern while sailing, as long as the shrouds are relatively tight (the only real worry is in a turtle situation where you could dismast). A new base ball would help, as would making sure the pin (shouldn't be a bolt) in the base of the mast is as large as will fit though the holes.
When lowering the mast, try to keep some forward/down pressure on the mast to keep the mast base engaged on the ball.
You don't know fear until you've had a Tiger mast come flying off the step. Timmmmmberrrrrrrr!