Failure to legally inbound ball after made goal

[chet_hoyt]

Ran into this scenario and wasn't sure I called it correctly...
A1 scored. B1 grabbed ball and walked to the endline to inbound, but in doing so was never actually completely out of bounds. His foot was clearly on the endline as he passed to B2, who walked the ball up the floor. I continued the 5 second count, thinking that they still could correct the error if they legally inbounded the ball within the 5 seconds. They didn't realize their error and were called for a 5-second inbound violation. Was this the correct call?

Thanks.