Strips are a totally unreliable way of measuring mash pH. You were probably OK until you added the baking soda and, if the conversion was going well it was probably complete or nearly complete before you brought it to a stop and you might be OK. The problem going forward is that kettle pH will be too high and pH in the fermentor will be too high but if you pitch enough strong, healthy yeast they may be able to overcome this and the beer may turn out OK.
These comments are based on the assumption that you are brewing a more or less nominal beer. If you are brewing a stout with a ton of roast/dark crystal then the pH may indeed have been too low and adding the bicarbonate may have saved the day. Note that this would not be the case with all stouts - adding bicarbonate to some stouts can be detrimental to them too.
If you are even going to think about taking action based on mash pH you must get a pH meter. Using strips will only lead you into trouble. They nearly always (for reasons which mystify me*) indicate that the mash pH is 0.3 or more lower than it actually is. This is, of course, not a bias upon which you can rely. If it were you could just add 0.3 to the reading and be back on track.
*One guy posted a picture of the strip he had used to test his mash with the color patches on the label of the container the strips came in. The color of the strip which had been immersed in the mash was not between any color pair on the legend so little wonder he couldn't read the mash pH correctly. This suggests that the colored components of mash/wort are interfering with the dye in the strips. Maybe that's the explanation.