88 trooper 2.6 starter staying on

i tried to start my truck this am and the starter kept going even after I turned the key off, I had to pull the bat cable. After I let things sit for a min or two I tried again and no problem. Could this be a sign of starter relay failure??It has 189k on it.

PS problem has not yet re acured but I have only started it 10 or so times since then.