Probably no big deal. In the course of changing struts, it would be very likely that the sensors would be removed to get the wire out of the way. These things are very fragile, and break easily when pulled.
Also may not have been reinstalled properly, or wires could have been damaged in process. Sensor wire is secured with plastic clip on strut, and may not have been resecured properly. Anyways, none of this is a big deal. Worst case, you actually need a brake job...
1986 300E 5-Speed 240k mi.