There are multiple different silanes or siloxanes that give signals in this range. It could be TMS but one often sees "joint grease" there or other compounds that can be leached out of for example rubber seals in disposable syringes.

Don't agree with most answers given above, for TMS should give a peak at 0.00 ppm (at it is the chemical shift reference defining the origin of the chemical shift scale). Most likely, your peak is due to some kind of "silicone grease". Refer to Fulmer et al., Organometallics vol 29 (2010) p 2176. You can easily distinguish the signal of tetramethylsilane from that of grease by evaluating the 29Si satellites; the coupling constant for TMS is 6.8 Hz but somewhat larger for the silicones (7.3 Hz).

I strongly support Wolfgang Baumann's answer.

G. R. Fulmer et al., Organometallics 2010, 29, 2176-2179 gives the 1H and 13C chemical shifts of ca. 40 common impurities in 12 different deuterated solvents.

Also a good source:

NMR Chemical Shifts of Common Laboratory Solvents as Trace Impurities

Gottlieb et.al. J. Org. Chem., 1997, 62 (21), pp 7512–7515

see the following ref.: Gregory R. Fulmer, et al, Organometallics 2010, 29, 2176–2179

TMS and "silicone grease" are readily distinguished in DOSY experiments since they have rather different molecular weights and, hence, diffusion coefficients.

You could deliberately add TMS to see if the peak gets larger at -.08 ppm. If it gives a separate peak at 0.0 ppm, then it is not TMS. I know this answer is obvious, but sometimes simple experiments can help.