Hi,
Yes, opioids are contraindicated with MAOI's (caapi, Syrian rue, etc) and can cause serotonin syndrome.
It shouldn't be too hard to go without that small of an amount of weak opiates for a week though.
I would be on the cautious side and go without it until it has completely gone out of your system.
I am currently trying to get off of buprenorphine to be able to drink a brew, but it is difficult.
Someone with more first hand experience with ayahuasca would be able to give more details than me.
Always err on the side of caution, though. You do NOT want a dangerous interaction while on powerful psychedelics.
Not a fun time.
I would do a bit more research on ayahuasca before going into it, though.
There is loads of info here to read and prepare yourself a bit better.
Good luck, be safe and I hope you have a great experience.