replaced catalytic after accident - now using loi - no leaks

Further info - low oil light came on next day after picked up from shop - took it back - said the oil plug was cracked and leaking oil - said put oil in and new plug; next day while sitting in parking lot I started car and white smoke filled the lot then went away - a neighbor says he can see some smoke out the exhaust after car is sitting for awhile. Engine runs great - had a compression check done but all cylinders good, No misfires - PVC OK. Coincidental? Ran without oil? Any catalytic issues (wrong kind - installed wrong - damaged)?