Used an at-home covid pcr test from labcorp & it came back negative... should i take it at face value or get retested if i've still got a slight sore throat & post nasal drip?

The PCR test is highly accurate but the sample collection is important. If the sample was adequate, the test is most likely accurate. The few days prior to symptoms until a few days after is the typical frame for most testing. A second home kit test may be indicated if you worsen and have shortness of breath.

If you still have symptoms, you can take a second test at least 24 hours apart from the first test. Follow the instructions carefully-assuming you are doing a nasal swab, swab both nostrils with the same swab. This will increase the probability of getting a good sample. If unvaccinated, and you test negative, get a vaccine ASAP! Best of luck to you!