Abstract: In the context of exoplanetary systems, secular resonances occur when two planets' long-term (secular) precessions align. When this occurs, angular momentum is exchanged between planets in greater magnitude and can excite large mutual inclinations and eccentricities. This can have potentially drastic impacts on system stability and detectability via transit. Typically, in a 3+ planet system, this results in the innermost planet becoming misaligned from the outer planets, and the outer planets aligning together. We show that including the effects of stellar spin evolution significantly broadens the range of the parameter space that allows resonances, greatly expanding the number of systems that may be in resonance or were in the past. Notably, the stellar spin can excite a system, and permanently freeze it in a high mutual inclination state. We explore 36 three-planet systems of transiting planets and find that at least 20% of them are in configurations susceptible to resonance. This means that linear secular resonances are likely a common feature of multi-planet architecture. Moreover, the impact these resonances caused by stellar spin-down have on transit probabilities presents a novel pathway for the constraint of the (presently old) host star's spin when it was young.