If a lender takes a mortgage on a dwelling as an abundance of caution, does the lender have to be a MLO?

If it's a consumer loan and secured by a 1-4 family dwelling, then yes. Abundance of caution only gets you out of appraisal requirements. A deed filed on a dwelling as an abundance of caution is still a lien on a dwelling.

If this is an isolated situation, this lender may fall under the de minimus rule. However, at our institution, we registered all loan officers that might touch real estate, because it would be a nightmare to try to monitor which ones had done less than 5 real estate loans in the previous 12 months.

This may be semantics, but for SAFE Act purposes there is no requirement that only an MLO can deal with mortgage loans; there's only a requirement that MLOs (who don't meet the de minimus exception mentioned above, if your bank wants to play that game) get registered with NMLS. If a violation were to exist, you would get cited for having an unregistered MLO, not for having a non-MLO deal with a mortgage loan.

Thanks all!