Yes it will definitely do that. Krausen sometimes sticks for a long time too and floating in hop matter will affect it to. As will motion, so hopefully you don't have your carboy next to the washing machine.
Don't expect the Tilt to be a precision measuring device but rather a tool to show you where you are in the fermentation process. I calibrate every batch in Starsan to 1.0 (I know, its probably off 0.001 or 2) and then calibrate to match whatever my refractometer reads for my OG. The FG has been close enough I no longer compare to a regular hydrometer. since all I really care about is knowing the approximate ABV at that point. In between it *may* do all sorts of crazy stuff because its just a plastic tube floating in actively fermenting beer. The cloud log will show a definite profile over time though and it will be obvious on the chart when fermentation ends. I love mine since I ferment in stainless vessels and can't see anything besides blowoff activity unless I pull samples.