When you swap your pre filters etc, it's wise to leave your system to run for a good while and let all the loose particles run through etc, hence your readings.
Or
Flush it, if you have a flush valve.
It's also worth noting, not to get into a panic and then start making rookie mistakes because of 2nd guessing things. It will be fine! Though, don't fall into this trap of thinking 005 isn't going to clean the windows as good and leave spotting! Trust me, it won't! My water goes in at just short of 300 tds and leaves the RO between 006 n 009 (can't recall which one it is, as I haven't had the need to check for a good while) and I haven't used resin for such a long time now. It fills up my ibc tank and I transfer it to the van and go work.