1998 Oldsmobile 88 Brake issue

Of course you should have it checked. The ability to stop is a dandy one and one you don't want to give up. You can check the level of the brake fluid first, but if the red brake warning light didn't turn on, this is going to a problem with the anti-lock function. There is going to be a diagnostic fault code stored in the computer. Those codes do not say to replace a part or that one is defective. They only indicate the circuit or system that needs further diagnosis. Don't disconnect the battery or let it run down as that will erase the codes. That information is the starting point in the diagnosis and the codes are especially valuable when the problem acts up intermittently.